HP-MPI User's Guide (11th Edition)

Understanding HP-MPI
Running applications on HP-UX and Linux
Chapter 3 81
This places ranks 0 and 2 on hosta and ranks 1 and 3 on hostb. This placement
allows intrahost communication between ranks that are identified as
communication hot spots. Intrahost communication yields better performance
than interhost communication.
Multipurpose daemon process HP-MPI incorporates a multipurpose
daemon process that provides start–up, communication, and termination
services. The daemon operation is transparent. HP-MPI sets up one
daemon per host (or appfile entry) for communication.
NOTE Because HP-MPI sets up one daemon per host (or appfile entry) for
communication, when you invoke your application with -np x, HP-MPI
generates x+1 processes.
Generating multihost instrumentation profiles When you enable
instrumentation for multihost runs, and invoke mpirun either on a host
where at least one MPI process is running, or on a host remote from all
your MPI processes, HP-MPI writes the instrumentation output file
(prefix.instr) to the working directory on the host that is running rank
0.
mpirun.all
We recommend using the mpirun launch utility. However, for HP-UX and
PA-RISC systems, HP-MPI provides a self-contained launch utility,
mpirun.all that allows HP-MPI to be used without installing it on all
hosts.
The restrictions for mpirun.all include
hosta
process 0
process 2
hostb
process 1
process 3
Fast communication